syzbot

IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready

======================================================
[ INFO: possible circular locking dependency detected ]
4.9.111-g03c70fe #5 Not tainted
-------------------------------------------------------
syz-executor234/3807 is trying to acquire lock:
 (rtnl_mutex){+.+.+.}, at: [<ffffffff830b4937>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
but task is already holding lock:
 (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff83345839>] lock_sock include/net/sock.h:1404 [inline]
 (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff83345839>] do_ip_setsockopt.isra.13+0x269/0x2b10 net/ipv4/ip_sockglue.c:636
which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

       lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
       lock_sock_nested+0xc6/0x120 net/core/sock.c:2511
       lock_sock include/net/sock.h:1404 [inline]
       ip_mc_config+0x147/0x1f0 net/ipv4/devinet.c:565
       inet_rtm_newaddr+0xb1b/0xef0 net/ipv4/devinet.c:868
       rtnetlink_rcv_msg+0x49c/0x650 net/core/rtnetlink.c:4059
       netlink_rcv_skb+0x145/0x370 net/netlink/af_netlink.c:2358
       rtnetlink_rcv+0x2a/0x40 net/core/rtnetlink.c:4065
       netlink_unicast_kernel net/netlink/af_netlink.c:1278 [inline]
       netlink_unicast+0x4d8/0x6f0 net/netlink/af_netlink.c:1304
       netlink_sendmsg+0x795/0xc30 net/netlink/af_netlink.c:1852
       sock_sendmsg_nosec net/socket.c:635 [inline]
       sock_sendmsg+0xcc/0x110 net/socket.c:645
       ___sys_sendmsg+0x6fc/0x840 net/socket.c:1969
       __sys_sendmsg+0xd9/0x190 net/socket.c:2003
       SYSC_sendmsg net/socket.c:2014 [inline]
       SyS_sendmsg+0x2d/0x50 net/socket.c:2010
       do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
       entry_SYSCALL_64_after_swapgs+0x5d/0xdb

       check_prev_add kernel/locking/lockdep.c:1828 [inline]
       check_prevs_add kernel/locking/lockdep.c:1938 [inline]
       validate_chain kernel/locking/lockdep.c:2265 [inline]
       __lock_acquire+0x3019/0x4070 kernel/locking/lockdep.c:3345
       lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
       __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       mutex_lock_nested+0xc0/0x870 kernel/locking/mutex.c:621
       rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
       mrtsock_destruct+0x3b/0x1e0 net/ipv4/ipmr.c:1231
       ip_ra_control+0x2c2/0x420 net/ipv4/ip_sockglue.c:360
       do_ip_setsockopt.isra.13+0x15ff/0x2b10 net/ipv4/ip_sockglue.c:1137
       ip_setsockopt+0x3a/0xb0 net/ipv4/ip_sockglue.c:1240
       raw_setsockopt+0xb7/0xd0 net/ipv4/raw.c:833
       sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:2706
       SYSC_setsockopt net/socket.c:1772 [inline]
       SyS_setsockopt+0x166/0x260 net/socket.c:1751
       do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
       entry_SYSCALL_64_after_swapgs+0x5d/0xdb

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sk_lock-AF_INET);
                               lock(rtnl_mutex);
                               lock(sk_lock-AF_INET);
  lock(rtnl_mutex);

 *** DEADLOCK ***

1 lock held by syz-executor234/3807:
 #0:  (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff83345839>] lock_sock include/net/sock.h:1404 [inline]
 #0:  (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff83345839>] do_ip_setsockopt.isra.13+0x269/0x2b10 net/ipv4/ip_sockglue.c:636

stack backtrace:
CPU: 1 PID: 3807 Comm: syz-executor234 Not tainted 4.9.111-g03c70fe #5
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d96275f8 ffffffff81eb2729 ffffffff8559cef0 ffffffff855e79b0
 ffffffff8559cef0 ffff8801d95888e8 ffff8801d9588000 ffff8801d9627640
 ffffffff814263a4 0000000000000001 00000000d9588000 0000000000000001
Call Trace:
 [<ffffffff81eb2729>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb2729>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff814263a4>] print_circular_bug.cold.51+0x1bd/0x27d kernel/locking/lockdep.c:1202
 [<ffffffff81239189>] check_prev_add kernel/locking/lockdep.c:1828 [inline]
 [<ffffffff81239189>] check_prevs_add kernel/locking/lockdep.c:1938 [inline]
 [<ffffffff81239189>] validate_chain kernel/locking/lockdep.c:2265 [inline]
 [<ffffffff81239189>] __lock_acquire+0x3019/0x4070 kernel/locking/lockdep.c:3345
 [<ffffffff8123ac50>] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
 [<ffffffff839edf90>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
 [<ffffffff839edf90>] mutex_lock_nested+0xc0/0x870 kernel/locking/mutex.c:621
 [<ffffffff830b4937>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 [<ffffffff83484e6b>] mrtsock_destruct+0x3b/0x1e0 net/ipv4/ipmr.c:1231
 [<ffffffff83345472>] ip_ra_control+0x2c2/0x420 net/ipv4/ip_sockglue.c:360
 [<ffffffff83346bcf>] do_ip_setsockopt.isra.13+0x15ff/0x2b10 net/ipv4/ip_sockglue.c:1137
 [<ffffffff8334811a>] ip_setsockopt+0x3a/0xb0 net/ipv4/ip_sockglue.c:1240
 [<ffffffff833ea1e7>] raw_setsockopt+0xb7/0xd0 net/ipv4/raw.c:833
 [<ffffffff8301c75a>] sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:2706
 [<ffffffff83019516>] SYSC_setsockopt net/socket.c:1772 [inline]
 [<ffffffff83019516>] SyS_setsockopt+0x166/0x260 net/socket.c:1751
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f8cd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb